JP4675242B2 - In-vehicle wireless communication device - Google Patents

Description

  The present invention relates to an in-vehicle wireless communication apparatus, and more particularly to a demodulator for demodulating a digitally modulated wireless communication signal and an in-vehicle receiver using the demodulator.

In recent years, in-vehicle field, in-vehicle wireless communication systems such as ETC (Electronics Toll Collection) and DSRC (Dedicated Short Range Communication) have been put into practical use, and wireless communication between in-vehicle devices and roadside devices has been implemented by digital wireless communication. Yes. ETC is already operating as an automatic toll collection system for expressways. These systems are standardized in ARIB-STD-T75 and the like. That is, this system uses a carrier frequency of 5.8 GHz band by wireless communication between the vehicle-mounted device mounted on the vehicle and the roadside device provided on the roadside. In addition, according to the ARIB-STD-T75 standard, 7 channels are allocated for each of the uplink and the downlink, and the arrangement of each channel is as shown in FIG. In FIG. 8, the uplink and downlink channels are arranged in ascending order of frequency.
Further, in the ARIB-STD-T75 standard, the uplink frequency and the downlink frequency are paired, and as is clear from the channel arrangement of FIG. 8, channels that are 40 MHz apart are used in the uplink and the downlink. . For example, the uplink 7 channel is 5.815 GHz, the downlink 7 channel is 5.775 GHz, and the difference is 0.04 GHz or 40 MHz apart. In addition, in-vehicle devices are defined only by one-way communication or half-duplex communication in the standard.

By the way, various types of RF configurations of the receiver are conceivable, and in general, a superheterodyne system, a direct conversion system, an LO-IF system, or the like is adopted. Various RF configurations are also conceivable in the ARIB-STD-T75 standard system.
FIG. 7 shows a configuration diagram of a conventional receiving system RF. The receiver in the figure amplifies the output signal of an antenna 50 that receives a high-frequency signal, a band-limiting filter (BPF1) 51 that restricts the use band of all reception channels that use an input signal from the antenna 50, and a BPF1-51. A low noise amplifier (LNA) 52, a mixer (Mix) 53 for converting the output of the LNA 52 into an intermediate frequency, a variable frequency SYNVCO 59 for determining a mixing frequency of the mixer 53, and an intermediate frequency which is an output of the mixer 53 IFAMP 54 for amplifying the band signal, BPF 2-55 for band-limiting the output of IFAMP 54, ADC 1-56 for sampling the output of BPF 2-55 and converting it to digital data, and digital data converted by ADC 1-56 Demodulator 57 for demodulating the signal from S, and S And controller58 for controlling NVCO59, configured with a.

A method for demodulating an IF band signal by undersampling is disclosed in Patent Document 1 or Patent Document 2 as a prior art. By using undersampling, down-conversion to baseband, which is originally performed by an analog circuit, and a direct conversion circuit can be digitized, so that the analog circuit can be reduced in size and the sampling frequency of the ADC can be reduced. This makes it possible to lower the operating frequency of the demodulation processing by the above, and to realize a reduction in power consumption of the receiver.
As described above, in the ARIB-STD-T75 standard system, the transmitter / receiver channel is 40 MHz away. Therefore, when the RF frequency conversion for reception is mixed with a local transmitter having the same frequency as the transmission channel, the received IF signal is obtained. A signal centered at 40 MHz is obtained. In this way, the received RF signal is down-converted to an IF signal of 40 MHz and can be demodulated using an undersampling technique, so that the analog circuit can be downsized as described above. In addition, as described above, there is an advantage that a single local oscillator can be realized by transmission and reception.

FIG. 6 is a diagram showing the relationship between the received signal and undersampling. The vertical axis represents power level and the horizontal axis represents frequency. This shows how the 40 MHz reception signal 40 appears in the reception band centered on 8 MHz when the sampling frequency Fs is 32 MHz. That is, a 40 MHz reception signal 40 appears 8 MHz away from Fs (32 MHz), 24 MHz appears on the opposite side, and undersampling 41 and 42 appear on 8 MHz. However, in the undersampling method, since a half band of the sampling frequency is folded, it is necessary to sufficiently consider the influence of interference waves such as adjacent waves other than the received signal band. For this reason, as shown in FIG. 5, the band other than the received signal 33 must be sufficiently cut by a band limiting filter (BPF) (characteristic 32). That is, since the signals 34, 35, 31, and 30 appear in the bands of Fs / 2 and 3/2 * Fs, it is necessary to cut signals other than the reception signal 33 by a BPF having a filter characteristic such as 32.
JP-A-8-162990 JP 2003-318760 A

On the other hand, in the ARIB-STD-T75 standard system as described above, in order to communicate with the roadside device, the in-vehicle receiver needs to first search for a connectable channel while traveling. As shown in Fig. 8, the power search and FCMS (frame control message slot) from the roadside unit are detected in order from the downlink channels that exist in 7 channels, error check is performed by CRC verification, and whether it can be received normally. Need to check. The standard defines a frequency selection time, and a frame of a maximum of 9 slots is 9 frame times. In other words, a maximum of 63 msec per channel is required, and if all channels are in use and can be received, it is a maximum to search all channels and select a channel with good reception status and maximum power. A time of 441 msec is required. In the case of a vehicle that is traveling at a speed of 120 km / h, it will travel about 15 m.
In this way, in the case of a receiver using the undersampling technique, the IF band signal is input to the ADC by the LO-IF method and the modulation / demodulation process is performed by digital signal processing. On the other hand, there is a merit such as power consumption, but the signal input to the digital demodulator is limited to 1/2 the band of the sampling frequency, so the reception frequency is changed for each channel to receive the connection channel selection process. There is a problem that sufficient time is required to detect the power and confirm the received radio wave condition.

  In view of such problems, the present invention provides a receiver for an in-vehicle wireless communication apparatus using an undersampling method that samples at a frequency lower than the frequency of an IF band signal obtained by frequency-converting a high-frequency reception signal. Is limited by the signal band used, undersampling is performed, sampling is performed at a frequency more than twice the IF band frequency, and the local oscillator frequency is set so that all channels are placed below the IF frequency only when the reception channel is selected. To provide an in-vehicle wireless communication device capable of efficiently selecting a base station from a channel with the maximum power by determining the channel selection order from the calculated power spectrum in the descending order of the power value of each channel. Objective.

In order to solve such a problem, the present invention provides a band limiting filter for limiting an input signal from an antenna in a use band of all reception channels , an amplifier for amplifying an output signal of the band limiting filter, A mixer for converting the output of the amplifier into an intermediate frequency, a frequency variable local oscillator for determining a mixing frequency of the mixer, an intermediate frequency amplifier for amplifying an intermediate frequency band signal as the mixer output, and an output of the intermediate frequency amplifier An intermediate frequency band limiting filter for limiting the frequency of the signal, and a first AD converter that samples and converts the output of the intermediate frequency band limiting filter into digital data, and outputs the first AD converter. Is demodulated by digital signal processing, and the intermediate frequency band signal is converted by the first AD converter at a frequency lower than twice the reception intermediate frequency. A receiver for an in-vehicle wireless communication apparatus using an undersampling method that performs sampling, a high-pass filter for cutting off the DC component of the intermediate frequency, and an intermediate frequency band signal that has passed through the high-pass filter A second AD converter that samples the output of the intermediate frequency amplifier at a frequency that satisfies a Nyquist condition that is twice or more the signal frequency of the intermediate frequency band, and a power spectrum of the output of the second AD converter. The frequency of the local oscillator is set so that all channels are arranged below the intermediate frequency band only when the power spectrum calculation unit and the reception channel are selected, and the output of the intermediate frequency amplifier is set to the second AD converter Is used to sample digital data, and the output signal of the power spectrum calculation unit is used to output a plurality of reception channel signals. From each channel power calculated value, by the level determination for each channel signal, characterized by comprising a channel selector for determining a channel selection order from the maximum power channels in descending order of power, the.

In addition to the first AD converter for undersampling after passing through an intermediate frequency band limiting filter that limits the intermediate frequency signal in the used signal band, the present invention provides a high frequency band for cutting DC components from the intermediate frequency signal. All channels (downlink and uplink) are placed below the intermediate frequency only when the reception channel is selected using the second AD converter that samples at a frequency that is at least twice the frequency of the intermediate frequency band through the pass filter. In this way, the local oscillator frequency is set, the power spectrum is calculated from the output signal of the second AD converter including the signals of all channels , and the channel selection order is set in descending order of the power value of each channel from this power spectrum. decide.

According to a second aspect of the present invention, there is provided a band limiting filter that limits an input signal from an antenna in a use band of all reception channels , an amplifier that amplifies an output signal of the band limiting filter, and a mixer that converts an output of the amplifier to an intermediate frequency. A variable frequency local oscillator that determines the mixing frequency of the mixer, an intermediate frequency amplifier that amplifies the intermediate frequency signal that is the mixer output, and an intermediate frequency band limiting filter that limits the output of the intermediate frequency amplifier And an AD converter for sampling the output of the intermediate frequency band limiting filter and converting it to digital data, demodulating the output of the AD converter by digital signal processing, An undersampling method in which the intermediate frequency band signal is sampled by the AD converter at a low frequency is used. A receiver for an on-board wireless communication apparatus, wherein a high-pass filter for cutting a DC component of the intermediate frequency, an output of the intermediate-frequency band limiting filter, or an output of the high-pass filter is selected Only when selecting a receiving channel , set the local oscillator frequency so that all channels are arranged below the intermediate frequency, and switch by the selector to select the high-pass filter output, The intermediate frequency signal having a frequency component up to the intermediate frequency band signal component that has passed through the high-pass filter is changed to a frequency that satisfies the Nyquist condition of the sampling frequency of the AD converter more than twice the intermediate frequency, and the intermediate frequency signal The output signal of the frequency amplifier is sampled into a digital signal by the AD converter, and the power spectrum of the output signal of the AD converter is sampled. A power spectrum calculation unit for calculating a ram, and by determining the level of each channel signal from each channel power calculation value of the plurality of reception channel signals using the output signal of the power spectrum calculation unit, from the maximum power channel A channel selection unit that determines a channel selection order in descending order of power.

Instead of using the second AD converter as in claim 1, the sampling frequency of the AD converter is dynamically changed so that it can be realized by one AD converter. This eliminates the need to install two AD converters, and is advantageous in terms of cost. Further, the basic operation procedure is the same as that of the first aspect, but during channel selection, a signal is output by the selector so that the high-pass filter output signal for DC cut is used from the band-limited signal by the intermediate frequency band limiting filter. Switch the path. At the same time, the sampling frequency of the AD converter is increased. As a result, the power of all channels can be calculated, and the channel selection order can be determined.

According to a third aspect of the present invention, the power spectrum calculation unit calculates a power value of each channel frequency of the reception channel signal by performing frequency analysis by fast Fourier transform.
The power spectrum calculation unit for acquiring the spectrum information needs to be performed at high speed. For this purpose, it is advantageous in terms of speed to be realized by hardware. In the present invention, the power value of each channel frequency of the received channel signal is calculated by performing frequency analysis by fast Fourier transform (FFT).

According to a fourth aspect of the present invention, the power spectrum calculation unit arranges in parallel a band limiting filter group having a frequency of each reception channel as a center frequency and a bandwidth set to a modulation band, and outputs the band limiting filter output for each channel . The power value is calculated.
By arranging the band limiting filter groups in parallel, the power value of the band limiting filter output for each channel can be calculated, and the calculation speed can be increased.

According to the present invention, in the receiver of the in-vehicle radio communication device moving at high speed, to detect radio waves from the base station, by allowing check the power of all channels at a time, the efficiency from the channel of maximum power It is possible to select a base station well, and it is possible to select a base station reliably before a vehicle traveling at high speed passes through the communication area.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
FIG. 1 is a block diagram of an in-vehicle wireless receiving apparatus according to the first embodiment of the present invention. The in-vehicle wireless reception device 100 includes a BPF (band limiting filter) 2 that limits an input signal from the antenna 1 in a use band of all reception channels, and a low noise amplifier LNA (amplifier) 3 that amplifies an output signal of the BPF 2. Mix (mixer) 4 that converts the output of LNA 3 to an intermediate frequency, SYNVCO (local oscillator) 10 that can change the mixing frequency of Mix 4, and IF AMP (intermediate) that amplifies the intermediate frequency band signal that is the output of Mix 4 Frequency amplifier) 5, IF-BPF (intermediate frequency band limiting filter) 6 for band-limiting the output of IF AMP 5, and ADC (first AD conversion) that samples the output of IF-BPF 6 and converts it into digital data 7), an HPF (high pass filter) 11 for cutting off the DC component of the intermediate frequency, and H The ADC (second AD converter) 12 that samples the output of the IF AMP5 at a frequency that satisfies the Nyquist condition of the intermediate frequency band signal that has passed through the F11 at least twice the intermediate frequency signal frequency, and the output power of the ADC 12 The power spectrum calculation unit 13 for calculating the spectrum and the frequency of Mix4 are set so that all channels are arranged below the intermediate frequency band only when the reception channel is selected, and the output of IF AMP5 is digital data using the ADC 12 And the level of each channel signal is determined from each channel power calculation value of a plurality of reception channel signals using the output signal of the power spectrum calculation unit 13, so that the channel selection order is increased in order of power from the maximum power channel. A channel selector 14 for determining the And it is configured to include a controller 9 for controlling the whole, a.

The receiver shown in FIG. 1 includes an antenna 1 that receives a high-frequency signal, a band-limiting filter (BPF) 2 that restricts the use band of all reception channels that uses an input signal from the antenna 1, and a low-frequency amplifier that amplifies the output signal of the BPF 2. It comprises a noise amplifier (LNA) 3 and a mixer 4 for converting the output of the LNA 3 into an intermediate frequency. A local oscillator 10 is connected to the mixer 4 to determine a mixing frequency. The output of the mixer 4 is connected to the ADC 7 via the IF amplifier (IF amplifier 5) and the band-limiting filter 6 in the IF band, and the output end of the ADC 7 is connected to the demodulator 8.
During normal reception, the reception IF signal appears at 40 MHz by setting the frequency of the local oscillator 10 to the frequency of the selected transmission channel. At this time, if the sampling frequency of the ADC 7 is set to 32 MHz, the signal digitized by undersampling has a bandwidth of 0 Hz to 16 MHz, and the 40 MHz IF signal appears at 8 MHz. The above is the processing after the channel to be used is determined.

  In general, since the channel number used by the base station is not known, the channel used by the base station is searched first, then connection processing is performed, and data communication can be started after connection. Therefore, it is necessary to always be in a channel detection state while traveling. As described above, if the channel detection process is performed by changing the frequency of the local transmitter 10 for each channel, there is a possibility that a time of 441 msec is required for the detection process for seven channels. Therefore, the ADC 12 is used instead of the ADC 7 during channel selection.

  At this time, the frequency of the local oscillator 10 is set so that all channels appear at the output of the IF amplifier 5 as shown in FIG. In FIG. 3, since the DL7 channel has the lowest frequency, a margin of about 10 MHz is added to DL775's 5.775 GHz, and the frequency of local transmitter 10 is set to 5.765 GHz. At this time, in order to cut the DC component of the IF amplifier 5 output, it passes through the HPF 11 as shown in FIG. Further, the sampling frequency of the ADC 12 is set so that all the channels including the uplink channel are within the Nyquist frequency as shown in FIG. For example, sampling may be performed at 180 MHz including a margin.

The digital signal sampled by the ADC 12 is rearranged in order from the channel with the highest power based on the power value of each channel obtained through the power spectrum calculation unit 13 as shown in FIG. Based on this order, the controller unit 9 sets the frequency, returns to the normal reception mode, and analyzes the frame received by the ADC 7. Of course, a channel determined to have no power is excluded from reception. The determination may be performed using a threshold value.
In this way, the maximum power channel number can be detected in a short time, and the time required for the frequency selection process can be shortened.

  FIG. 2 is a block diagram of an in-vehicle wireless receiver according to the second embodiment of the present invention. The same components will be described with the same reference numerals as in FIG. The in-vehicle wireless reception device 110 includes a BPF (band limiting filter) 2 that limits an input signal from the antenna 1 in a use band of all reception channels, a low noise amplifier LNA (amplifier) 3 that amplifies an output signal of the BPF 2, Mix (mixer) 4 that converts the output of LNA 3 to an intermediate frequency, frequency-variable SYNVCO (local oscillator) 10 that determines the mixing frequency of mixer 4, and IF AMP (intermediate) that amplifies the intermediate frequency band signal that is the Mix 4 output Frequency amplifier) 5, IF-BPF (intermediate frequency band limiting filter) 6 for band-limiting the output of IF AMP 5, and ADC (first AD conversion) that samples the output of IF-BPF 6 and converts it into digital data 7) and HPF (High Pass Filter) 1 for cutting the DC component of the received intermediate frequency band 1 1, the selector 15 for selecting either the output of the IF-BPF 6 or the output of the HPF 11, and the local oscillator frequency is set so that all channels are arranged below the intermediate frequency only when the reception channel is selected. The output is switched by the selector 15 so as to select the output, and the intermediate frequency signal having the frequency component up to the intermediate frequency band signal component that has passed through the HPF 11 is converted to the Nyquist sampling frequency of the AD converter 7 more than twice the reception intermediate frequency band frequency. A power spectrum calculation unit 13 that changes the frequency to satisfy a condition, samples the output signal of the IF AMP 5 into a digital signal by the AD converter 7, calculates the power spectrum of the output signal of the AD converter 7, and a power spectrum calculation unit Calculation of each channel power of a plurality of reception channel signals using 13 output signals From the maximum power channel, the channel selection unit 14 for determining the channel selection order in descending order of the power by determining the level of each channel signal, the demodulator 8, and the controller 9 for controlling the whole are configured. Is done.

  In this embodiment, instead of using the ADC 12 as shown in FIG. 1, the sampling frequency of the ADC 7 is dynamically changed so that it can be realized by one ADC 7. This eliminates the need to install two ADCs, which is advantageous in terms of cost. The basic operation procedure is the same as described above, but during channel selection, the signal path is changed by the selector 15 so that the output signal of the DC cut HPF 11 is used from the band-limited signal by the BPF 6 as shown in FIG. Switch. At the same time, the sampling frequency of the ADC 7 is increased to 180 MHz. As a result, the power of all channels can be calculated, and the channel selection order can be determined as in the first embodiment.

The receiver of the in-vehicle wireless communication apparatus according to the present invention is an in-vehicle wireless using an undersampling method that samples a high-frequency received signal at a frequency lower than the frequency of the IF band signal obtained by frequency-converting the high-frequency received signal. In the receiver of the communication apparatus, after passing through the BPF 6 that restricts the IF signal in the use signal band as shown in FIG. 1, the IF band frequency is changed from the IF signal to the DC component cut HPF 11 in addition to the ADC 7 for undersampling. Using the ADC 12 that samples at a frequency of 2 times or more and setting the local oscillator frequency so that all channels (downlink and uplink) are placed below the IF frequency as shown in Fig. 3 only when the reception channel is selected. The power spectrum is calculated from the output signal of the ADC 12 including all channel signals. Determining the descending order in the channel selection order of power values of the respective channels from the power spectrum as a. In FIG. 4, the uplink is UL2, UL5. UL7 is selected in the order of UL1, and the downlink is selected in the order of DL2, DL5, DL7, DL1.
As a result, if the power is calculated for a certain period, the received power order of all the received channels can be determined at a time, so it is possible to efficiently select the channel by checking the received radio wave status in order from the maximum power channel. The time required for selection can be greatly reduced.

Alternatively, as in the second embodiment, the sampling frequency of the ADC 7 is made variable as shown in FIG. 2 and is set to the same frequency as the sampling frequency of the ADC 12 as described above only when the reception channel is selected. Similarly, the time required for channel selection can be greatly reduced.
The power spectrum calculation method for acquiring spectrum information as shown in FIG. 4 is such that the power spectrum calculation unit calculates the power value of each channel frequency of the received channel signal by performing frequency analysis by fast Fourier transform. And a method of calculating the power value of the band limiting filter output for each channel by arranging in parallel a band limiting filter group having the frequency of each receiving channel as the center frequency and setting the bandwidth to the modulation band There is.

1 is a block diagram of an in-vehicle wireless reception device according to a first embodiment of the present invention. It is a block diagram of the vehicle-mounted radio receiver which concerns on the 2nd Embodiment of this invention. It is the figure which set the local oscillator frequency so that all the channels may be arrange | positioned below IF frequency. It is a figure which determines a channel selection order from the power spectrum in order with the large power value of each channel. It is a figure showing a mode that a zone | band other than a received signal is cut by a band-limiting filter (BPF). It is a figure which shows the relationship between a received signal and undersampling. It is the conventional receiving system RF block diagram. It is an arrangement view of each channel in the ARIB-STD-T75 standard.

Explanation of symbols

  1 antenna, 2 BPF, 3 LNA, 4 Mix, 5 IF AMP, 6 IF-BPF, 7, 8 demodulator, 9 controller, 10 SYNVCO, 11 HPF, 12 ADC, 13 power spectrum calculation unit, 14 channel selection unit, 100 On-vehicle wireless receiver

Claims (4)

A band limiting filter for limiting an input signal from an antenna with a use band of all reception channels , an amplifier for amplifying an output signal of the band limiting filter, a mixer for converting the output of the amplifier to an intermediate frequency, and mixing of the mixer A variable frequency local oscillator for determining a frequency, an intermediate frequency amplifier for amplifying an intermediate frequency band signal as the mixer output, an intermediate frequency band limiting filter for band limiting the output of the intermediate frequency amplifier, and the intermediate frequency A first AD converter that samples and converts the output of the band limiting filter into digital data, and demodulates the output of the first AD converter by digital signal processing;
A receiver for an in-vehicle wireless communication device using an undersampling method in which the intermediate frequency band signal is sampled by the first AD converter at a frequency lower than twice the reception intermediate frequency;
A high-pass filter for cutting off the DC component of the intermediate frequency;
A second AD converter that samples the output of the intermediate frequency amplifier from the intermediate frequency band signal that has passed through the high-pass filter at a frequency that satisfies a Nyquist condition of at least twice the intermediate frequency band signal frequency;
A power spectrum calculation unit for calculating the power spectrum of the output of the second AD converter;
Only when a reception channel is selected, the frequency of the local oscillator is set so that all channels are arranged below the intermediate frequency band frequency, and the output of the intermediate frequency amplifier is digital data using the second AD converter. The channel selection order is determined in descending order of power from the maximum power channel by determining the level of each channel signal from each channel power calculation value of a plurality of reception channel signals using the output signal of the power spectrum calculation unit. An in-vehicle wireless communication apparatus comprising: a channel selection unit that determines A band limiting filter for limiting an input signal from an antenna with a use band of all reception channels , an amplifier for amplifying an output signal of the band limiting filter, a mixer for converting the output of the amplifier to an intermediate frequency, and mixing of the mixer A variable frequency local oscillator for determining a frequency, an intermediate frequency amplifier for amplifying an intermediate frequency band signal as the mixer output, an intermediate frequency band limiting filter for band limiting the output of the intermediate frequency amplifier, and the intermediate frequency An AD converter that samples and converts the output of the band limiting filter into digital data, and demodulates the output of the AD converter by digital signal processing;
A receiver for an in-vehicle wireless communication apparatus using an undersampling method in which the intermediate frequency band signal is sampled by the AD converter at a frequency lower than twice the reception intermediate frequency band;
A high-pass filter for cutting off the DC component of the intermediate frequency, a selector for selecting one of the output of the intermediate-frequency band limiting filter and the output of the high-pass filter;
Only when the reception channel is selected, the local oscillator frequency is set so that all channels are arranged below the intermediate frequency band, and the high-pass filter is switched by the selector so as to select the high-pass filter output. The intermediate frequency signal having a frequency component up to the intermediate frequency band signal component that has passed through is changed to a frequency that satisfies the Nyquist condition of the sampling frequency of the AD converter more than twice the intermediate frequency, and the output of the intermediate frequency amplifier A power spectrum calculation unit for sampling a signal into a digital signal by the AD converter and calculating a power spectrum of an output signal of the AD converter;
By determining the level of each channel signal from the calculated channel power values of the plurality of reception channel signals using the output signal of the power spectrum calculation unit, the channel selection order is determined in descending order of power from the maximum power channel. An in-vehicle wireless communication device comprising: a channel selection unit.   The in-vehicle wireless communication device according to claim 1, wherein the power spectrum calculation unit calculates a power value of each channel frequency of the reception channel signal by performing frequency analysis by fast Fourier transform. . The power spectrum calculation unit calculates a power value of the band limit filter output for each channel by arranging in parallel a band limit filter group having a frequency of each reception channel as a center frequency and a bandwidth set as a modulation band. The in-vehicle wireless communication apparatus according to claim 1 or 2, wherein

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